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New Constraints on Neutron- Capture Nucleosynthesis Processes

New Constraints on Neutron- Capture Nucleosynthesis Processes. Inese I. Ivans California Institute of Technology Hubble Fellows Symposium April 7, 2005. A Periodic Table of the Elements. 1. 2. H. He. BBN CR (+/-) neutron-capture. 3. 4. 4. 5. 6. 7. 8. 9. 10. Li. Be. B. C.

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New Constraints on Neutron- Capture Nucleosynthesis Processes

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  1. New Constraints on Neutron-Capture NucleosynthesisProcesses Inese I. Ivans California Institute of Technology Hubble Fellows Symposium April 7, 2005

  2. A Periodic Table of the Elements 1 2 H He BBN CR(+/-) neutron-capture 3 4 4 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 Fr Ra Ac 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr yy Xx: element symbol; yy: atomic number Xx

  3. Chart of Nuclides (Rolfs & Rodney 1988)

  4. Solar System Abundance Distribution =Z+N =Z+N (Cowley 1999)

  5. Solar System Abundance Distribution =Z+N SNeIa AGB SNeII O,Mg massive Si,Ca,Ti less massive Th,U t Sr,Y,Zr Ba,La Pb,Bi massive less massive =Z+N

  6. The site of the rapid neutron-capture process? Happened very early in Galactic times: some very metal-poor stars are enormously rich in elements created in r -process (eg. [Fe/H] ~ -3.1 => 1/1250 [Fe/H]sun) Created in SNe II Maybe Probably Likely Perhaps ... Sneden, Cowan, Ivans et al 2002

  7. “universality” of the r-process? • Happened over long • timescales and range • of metallicities and • in equal measure in • the disk and halo • Created in SNe II • Maybe • Probably • Likely • Perhaps ... (Cowan, Sneden, Ivans et al 2001)

  8. “universality” of the r-process maybe not so universal SS-r poor agree- ment with Z<56 &/or heavies BD+17o3248 (Cowan et al 2002)

  9. Lead & bismuth: the end of the line for the s-process (Rolfs & Rodney 1988)

  10. In low mass (1-3Msun) AGB stars, neutrons: 12C(p,g)13N(e+,n)13C(a,n)16O seeds: Fe With decreasing metallicity, n ~ constant Fe decreasing => increasing n/Fe => Ds-process dist’n (1998 Gallino et al.)

  11. CS29497-030 Largest [Pb/Fe] to date First Bi to be measured in a metal-poor star (Ivans et al. submitted)

  12. (Ivans et al. submitted)

  13. In Summary • CS29497-030: first abundance measurement of • Bi in a metal-poor star • Bi/Pb in accord with s-process predictions • overall abundance pattern fits that of (r+s) • process where s-processing includes r-process • pre-enrichment • abundance of Na (and other elements sensitive • to the neutron-excess) can be employed to • constrain the mass of the AGB progenitor: • lower mass stars go through fewer thermal, • producing lower abundances of elements • sensitive to the neutron excess

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